I would keep an eye on the weather, on Southwest's website, and on your airport's website. If suddenly it looks like Sat might be a problem, perhaps you will be allowed the ability to switch to Friday. (or, well, with SW you could do that now, but maybe they wouldn't charge you more if it's weather-based...not sure how that works with SW!) That would necessitate work/school changes and another hotel night, but it would be better than possibly missing the cruise!
Recently Freedom of the Seas cruise...as we left the ship for a fun port day in St Maarten we saw a couple, each carrying LARGE rolling suitcases, not carry-on types, towards our ship. They didn't look sun-kissed, didn't look happy. We got the distinct impression that they had somehow missed the Canaveral embarkation, and they were now meeting the ship. Our cruise embarked in PC on the 26th, and this was the first "distant foreign port" where they could have joined us (previously Cococay, at sea, and San Juan), and it was the 30th. If our read on the situation was correct, you don't want to be them. So keep a, ha, weather eye out.